Unit heater control



Patented .I'ulyl, 19a

.nnnonn w. swam, or-irmnnaroms, MINNESOTA, Assmnon, BY MESNE assren- MEN'IS, 'ro mmnrnoms-nonnrwnu. REGULATOR comm, or mmmaroms, MINNESOTA, A .conronarron or DELAWARE UNIT HEATER CONTROL Application and June 10,

This invention .relates generally 'to improvements in heat regulating devices and is.

ranged adjacent the outer wall of a building.

and, inasmuch as conduits are often provided so that cold outside air may be delivered to the radiator, operation of the fan when the radiator is'cold would result in a cold draft being forced into the building, or the 'fan would create a cold draft which'is also undesirable. Moreover, in hot water systems, or in steam systems in which the drainage'is imperfect, it may happen that if the fan starts at a time when there is no heat in a radiator, the water of condensation may be frozen whichmight result and sometimes does result in cracking of the radiator. Also under these conditions, when thawing takes place, a considerable amount of damage may be done by leaking water.

The main object of the invention is to provide means which will obtain and allow operation of the fan, as the result of temperature fluctuations in a room only when the heater has reached a predetermined temperature. Another object of the invention is to provide a very simple electrically operable means for controlling the operation of the fan. Another and more specific object is to provide a single rela operable and controllable through two evices, one dominating control of the other, one a thermostatically responsive device arranged in the room, and the otherla device responsive to fluctuations in heat'supplyat the heater. The arrangement is such that the room device can only operate to cause energ'ization ofthe fan motor when both heater and room devices are closed. The arrangement further is such that if the heater device is not closed the room device can haveno control-to start'th'e mo- 1927. serial No. 197,987. I

PATENT-OFFICE A ideaof controlling the fan of a unit heater by use of a single switch-controlling, or relay device, to, positively prevent running of the fan when the heater is cold, along with the detailed arrangement of the elements of the apparatus for. obtaining the results set forth herein.

The figure of the drawing diagrammatically represents the system, with motor not runnlng.

To show one application of the invention the following construction is illustrated:

The'fa'n'motor is indicated at 1 and this' motor is opposingly arranged in such relation to a radiator 13 as to circulate air heated by the heater. In this instance, primary circuit is provided and includes a transformer the primary coil of which is indicated at -2 and" the'secondary coil of which is indicated at 3. A single relay is used and has an armature '11- having a contact 6 cooperable with contact 5 of the high voltage circuit. Conductor 7 connects one side'of the motor 1 with one side of the main line-25, and conductor 8 connects at the opposite side of the motor with the contact 5, the opposite side 26 of the main line is connected by conductor 9 with the contact 6 of the armature 11. The relay coil is indicated at 10 and is connected with one side of the secondary 3 by conductor 15. The armaat I ture 11 is provided'with a contact 12 cooperable with contact13. A thermostatically responsive room device has a movable'member '7' having in this instance two electrically connected elements, respectively r'- and 1' respectively engageable with two contacts bw. These elements 1"'-r are sequentially engage able with the contacts 6-40. Element r? is first to engage and last to disengage, andelement 1" is last to engage and-first to disengage. A device responsive to fluctuations in heat supply atthe heater has a movable member 21, which member in this instance other, andrespectively designated R and R". 9

has a pair of elements insulated from one an- These elements are engageable respectively with contacts B-W, and make sequentlally R' first and R lastand in reverse order when breaking.

The coil 10 and contact 12 are connected by conductor 17 to contact B of the radiator device. The op osite side of the secondary side of the trans ormer 3 is connected by conductor 6 with contact W of the radiator device. Contact 13- is connected by conductor 18 with member-r of the roomdevice. It will'be noted that the elements 1", r are not insulated. Contact I) of the room device is connected by conductor 19 with elements R of the radiator device, and contact w of the room device is connected by conductor 20 with the element R of the radiator device.

The connections in the secondary circuit are so arranged between the room and the heater device of the relay, that the room de- 5 of the room device can be of a bimetallic structure, or of any structure which will'make it responsive to bend in opposite directions followin the fluctuations in temperature. It

will be urther understood that the element 21 may be either'a bimetallic element or a Bourdon tube or other device which can be affected when the radiator is hot to move in one direction and when the radiator is cooled to move in the opposite direction.

Operation The diagram shows the system inoperative with both room and radiator devices having their elements out of contact. In this position, therefore, the fan is not running because the radiator is suflici'ently cool to have caused breaking at both contacts, and the room thermostat is sufliciently warm to have also opened or broken both its contacts.

To show how the device operates to prevent energization of the fan motor when the heater is cold, let it be assumed, with the device posi-, tioned as shown in the illustration, that the room device cools sufliciently to make contact at rc0. Under these conditions, the coil 10 cannot be energized to close the motor control switch because the elements RR' are both spaced away from their contacts. Let us sup ose that, on continued cooling of the room t ermostat, the element r contacts b. It is evident that no circuit can pass through the conductor 19, element B because RB are out of contact. Let it be supposed the elements 1" radiator device heats sufiiciently to make at R'W. Even under these conditions no current can pass (conductor 20, R, W, 16, 3, 15,

10, 17 to B) because RB are not making.

Nor can current pass 19-13. for the same reason. vWhenever RB make, however, coil 10 is energized, motor control switch closes and the fan motor starts. Simultaneously 12-43 close and that part of the secondary circuit including elements r -R' act to hold. If when the fan is thus running either the room thermostat or the radiator device would move away from their contacts sufliciently to break either at r'b or at RB, or at both simultaneously or eitherone before the other, will still maintain the circuit in closed position and the fan will continue to run. Immediately, however, that either r or R break, either simultaneously or one before or after the other, the coil 10 will be energized andthe switch 11 opened to stop the motor.

It will thus be seen that the radiator device dominates the control, and that no control whatever can be had through the room device unless the radiator device is makingat both contacts BW. It will, however, be seen that if the relay circuit has been once closed, one of the contacts of each device may open and the circuit still be maintained in closed condition providing that one element of each device is making. 7

I claim as my invention:

1. A device of the class described comprising a heater, a motor having a fan arranged to circulate air warmed by the heater,

a device responsive to fluctuatlons in heat supply at the heater, a thermostatically responsive room device, each device having two contacts and a movable member having a pair of elements sequentially engageable with the contacts, a rimary circuit for the motor, a

v secondary circuit for the room and heater devices, a relay arranged to simultaneously close both circuits when its coil is energized,

the elements of the secondary circuit being so arranged that the room device can only operate to obtain energization of the motor, when both elements of the heater and room devices are closed.

2. A device of the class described comprising a heater, a motor having a fan arranged to circulate air warmed by the heater, a device res onsive to fluctuations in heat supply at the eater, a thermostatically responsive room device, each device having two contacts and a movable member having a pair of elements sequentially engageable with the contacts, and being disengageable sequentially in reverse order, a primary circuit for the motor, a secondary circuit for the room and heater devices, a relay arranged to simultaneousl close both circuits when its coil is ener 'ze the elements of the secondary circuit bemg'so -vice responsive to fluctuations in heat supply at the heater, a thermostatically responsive room device, each device having two contacts and a movable -memberhaving elements sequentially engageable with the contacts, the elements of the movable member of the heater device being insulated from one another, separate circuits respectively for the motor and, for the room and heater devices, a relay arranged to simultaneously close both circuits when its coil is energized, the elements of the device circuit being so arranged that the room device can ,only operate to cause energization of the 'motor when both elements of both devices are closed, the arrangement further being such that one element of each device acts .to hold the relay'in circuit closing position after the other elements of the device have broken contact.

4. A device of the class described comprising a'heater, a fan motor arranged to circulate air warmed by the heater, adevice re-- sponsive to fluctuations in heat supply at the heater, a thermostaticall responsive room device, each device having two contacts and a movable member having elements sequentially engageable with the contacts, the elements of the movable member of the heater device being insulated from one another, separate circuits respectively for the motor and for the room and heater devices, a relay arranged to simultaneously close both circuits when its 'coil is energized, the elements ofthe device circuit being so arranged that the room device can only operate to cause energization of the motor when both elements of both devices are closed.

5. A device of the class described comprising a heater, a fan motor arranged to circulate air heated by theheater, two thermostatic-devices each having contacts and a movable element engageable therewith, one device arranged to be eliected only by heater temperatures, a circuit for the motor, a single coil relay controlled by the thermostatic devices, and including a circuitso arranged that the relay coil can only be energized when the thermostatic device at the heater is closed, said relay controlling both thermostatic and motor circuits and the arrangement further being such that the motor can only initially receive current if all contacts of both devices are electrically closed.

6. A device of the class described comprising a heater, a fan motor arranged to circulate air heated by the heater, twothermostatic devices each having contacts and a -movable element having portions sequent1allyengageable' therewith,one device arrangedto'be afl'ectedonly-by heater temperatures, a circuit for the motor, "a single coil relay controlled by the thermostatic devices, and including a circuit so arranged that the relay coil can only be energized when the thermostatic device at'the heater'is closed,

said relay controlling both thermostatic and motor circuits, and the arrangement being such that after such closure, one contact of one of the thermostatic devices can open with-. out de-energizing the relay coil. V

7. A device of the class described comprising a heater, a motor having a fan arranged to circulate air warmed by the heater, adevice responsive to fluctuations in heat supply at the heater, a thermostatic responsive room device, each device having two'contacts and a movable-member arranged to sequentially engage the contacts in one order and to 'be dis engaged therefrom in a reverse order, a motor' circuit, a relay arranged to control the circuit, and circuit connections between the relay and the thermostatic devices, such that the room device can only operate," to obtain energization of the motor when both contacts of the radiator device are closed.

static devices, suchthat the room device can only operate, to obtain energization of the motor when both contacts of the radiator device areclosed, andsuch that after motor energization such energizationis maintained if the movable elementof the room device engages at least onefof its contacts.

9. A device of the class'described including two temperature-controllable devices each having two contacts and a movable element engageable therewith, electrically operable controlling means including a contact controlled by said means, and circuit connections for the elementsof'the temperature-controllable devices in which one contact-of each de viceis in series relation with said electrically operable means: and Contact controlled thereby, and in "whichall contacts of both devices are in series 7 relation 'withisaid electrically operable means "through 'a'circuit which does not includej'the contact of said electrically op} erable means. j" f y i v y .10. Adevicejof theclass descrih ed incl d ing two temperature-controllable devices each having, 'twoicontacts, and a ievab1e**-e1e h fie e ag abl er w h Ql ti bl controlling means including a contact con- 11. A device of the class described compris ingaheater, a motor having a fan arranged to circulate air warmed by the heater, two temperature-controllable devices each having two contacts and a movable element engageable with said contacts, one device responsive to heat' fluctuations at the heater, electrically o erable means for controlling the motor an including a contact and circuit connections for the elements of the temperature controllable devices in which one contact of each device is in series .with said electrically operable motor controlling means and contact, and in which all contacts of both devices are in series with said electrically operable means through a' shunt which does not include the contact.

12. A device of the class described comprising a heater, a motor having a fan arranged to circulate air warmed by the heater, two temperature-controllable devices each having two contacts and amovable element engage- I able with said contacts, one device responsive to heat fluctuations at the heater, electrically operable means for controlling the motor and including a contact which closes when said means is energized, and circuit connections for. the elements of the temperaone device responsive to heat having, contacts,

electrically o rfluctuations at the heater,

able means for controlling the motor an mcluding a contact which closes when the relay is energized, and circuit connections for the elements of the temperature-controllable devices in which one contact of each device is in series with said electrically operable means and contact, and in which all contacts of both devices are in series with said meansthrough a shuntwhich does not include the contact.

In witness whereof, I have hereunto set my hand this 6th day of June, 1927.

HAROLD W. SWEATT.

tare-controllable devices in which one con- 7 tact of each device is in series-with said electricallyoperable means and contact, and in s onsive to heat which all contacts of both devices are in series with said means through a shunt which does not includethe contact.

13. A device of the class described comprising a heater, a motor having a fan arranged to circulate air warmed by the heater, two temperature-controllable devices each having two contacts and a movable element se uentially engageable with said contacts, one evice refluctuations at the heater, e cctrically operable means for controlling operation of the motor and includin a contact, and circuit connections for the e ements of the temperature-controllable devices, in which one conta'ctof each device is in series with said electrically operable .means and contact, and all contacts of both devices are 'in series with said means-through a. shunt which does notinclude the contact.

-' 14 A device of the class described comprism ran to circulate air warmed b the heater, two temperature-controllable evices each a heater, a motor having a fanjar- III III 

